1. Field of the Invention
The invention relates generally to the shattering of earth formations and earth formation removal by the detonation of explosives within boreholes formed in the earth formations. The invention specifically relates to inflatable devices used to support explosives and/or stemming materials within a borehole and which are capable of use in large diameter boreholes such as boreholes having a diameter of up to approximately 48 inches and also in particular blasting techniques such as vertical cratering.
2. Description of the Prior Art
The improvement of various mining and earth removal operations has been fully disclosed by Fitzgibbon, Jr. in U.S. Pat. Nos. 4,913,233; 4,919,203; 5,000,261 and 5,035,286, the disclosures of which are incorporated hereinto by reference. Reference to the Fitzgibbon patents provides a full description of the prior art relative to practices known as "presplitting", that is, shattering of earth formations in a controllable manner prior to the use of techniques generally referred to as "production" blasting. In both presplitting and production operations, explosives and/or stemming materials are suspended within boreholes with detonation occurring according to established practices. The inflatable devices and methods disclosed for their use such as are disclosed in the Fitzgibbon patents are of substantial utility in the art since they are of simple and inexpensive construction yet are capable of supporting explosives and/or stemming in boreholes of widely varying diameter. The art is hereby improved by inflatable devices configured for use particularly in large diameter boreholes and in blasting applications such as vertical cratering. Even in boreholes having diameters of up to approximately 48 inches, the present inflatable devices exhibit improved ability to suspend explosives and/or stemming materials at desired locations within boreholes. The present inflatable devices thus constitute a significant and substantial advance in the art.